The present invention relates to electric energy meters, and more particularly to a multifunction electronic register configured to be selectively added to a watthour meter.
The use of electronics in electric energy meters has enabled the design of energy meters with greatly increased capability and functions. However, there is increasing pressure for such meters to have fewer parts and to be substantially smaller than previous designs, and to incorporate additional capability and functions. Fewer parts are required in order to minimize manufacturing costs, including the cost of materials and assembly, and the subsequent cost and number of components which must be maintained for spare parts and repair purposes, along with an increase in reliability which accompanies designs which have fewer parts.
In electronic registers, it is well known to utilize an electro-optical link to read time of use of energy consumed by the load being metered, and also to program the microprocessor with desired time of use metering information from outside the energy meter without removing the cover. In a combination induction electric watthour meter and time of use electronic register, the watthour meter utilizes an eddy current disk which rotates in response to the rate of energy consumption by the load being metered. A shutter is commonly mounted on the same shaft as the eddy current disk, and is positioned to rotate between a light emitter and a light detector pair. A plurality of circumferential teeth on the rotating shutter sequentially break the light beam between the light emitter and light detector pair to provide a series of electrical pulses, the frequency of which is directly proportional to the rate of energy consumption by the load being metered. An optical communications link between the energy meter optical system and the outside of the meter is provided for interfacing to a portable reader, providing a means for extracting billing data and for programming the energy meter.
The use of such multiple optical transmission paths within the electronic register provides problems of accurately positioning and retaining a multiplicity of optical electronic components within the electronic register.
In addition, it is highly desirable to simplify the manufacture of electric energy meters, which would decrease the cost of manufacture and assembly, by minimizing the number of parts required and thus lower the cost and problems associated with stocking spare parts and providing repairs. Electronic registers are optional features to provide time of use or demand of energy consumption data for billing purposes in addition to providing the total watthour or kilowatthour power consumption. As such, it is desirable to be able to selectively add an electronic resister to a standard watthour meter design, which is typically produced in large volumes. This enables the manufacturer to obtain the benefits of the large scale production of the standard kilowatthour meter, and the ability to optionally provide an electronic time of use register when required by the customer. Furthermore, various optional features such as switch closure output signals and multifunction switching are desirable as selective additions to the energy meter.